The present invention relates generally to pressure regulators, and more particularly, to a diaphragm actuated absolute pressure regulator.
The assignee of the present invention manufactures missile systems that use a focal plane array infrared sensor that requires cooling to approximately 90.degree. K. The focal plane array and infrared sensor is disposed within a compartment on the missile. The temperature of the focal plane array and infrared sensor must be maintained within a few tenths of a degree Kelvin for precise target acquisition. Joule-Thompson coolers using argon or nitrogen gas are employed to cool the focal plane array infrared sensor. A constant supply of gas vents into the compartment housing the focal plane array infrared sensor from the Joule-Thompson cooler which must be vented.
During cooldown, large variations in the pressure within the compartment housing the focal plane array infrared sensor would result in temperature excursions due to the thermodynamic properties of the gas supplied to the Joule-Thompson cooler. A pressure regulator is required on high altitude missiles, and specifically those that travel to altitudes in excess of 60,000 feet, to prevent over or under venting of the compartment housing the focal plane array infrared sensor.
The currently used pressure regulator design incorporates bellows to regulate the flow of gas. Vacuum is drawn on the bellows, and the bellows are spring loaded to apply a force equivalent to that which would be applied by atmospheric pressure at sea level (14.696 psia). Welded bellows are costly, require a great deal of space, and are unreliable because of many welds that are required to manufacture the bellows. It has been found that after several uses, the bellows have been found to leak, thus destroying the internal vacuum within the bellows, compromising the pressure in the compartment housing the focal plane array infrared sensor and the Joule-Thompson cooler.
Accordingly, it is an objective of the present invention to provide for a diaphragm actuated absolute pressure regulator. It is a further objective of the present invention to provide for a diaphragm actuated absolute pressure regulator that may be used to vent a compartment housing a focal plane array infrared sensor employed on a high altitude missile system.